1. Technical Field
The present invention relates to an X-linked lift mechanism used for a hospital bed, home nursing care bed, facility bed, general bed, consultation seat, lift table, etc.
2. Description of the Related Art
For example, as mechanisms for lifting a lift frame relative to a base frame, as used for a bed or lift table, available are many parallel-linked lift mechanisms using parallel-linked mechanisms and X-linked lift mechanisms using X-linked mechanisms. This invention relates to an X-linked lift mechanism.
In the conventional X-linked lift mechanisms proposed, for example, in Patent Document 1 and Patent Document 2, the respective ends of first links and second links on one lateral side are pivotally rotatably fixed to a base frame and a lift frame, and the moving members installed at the respective ends of the first and second links on the other lateral side are engaged with the guide members installed on the lift frame and the base frame respectively. In this configuration, the moving members installed at the tips of the action links connected with the other lateral side portions of the second links are engaged with the guide members installed on the other lateral side portions of the first links, and a lineal′ actuator is provided to extend between the one lateral side portions of the first links and the moving members. Therefore, in this lift mechanism, the lift frame is raised when the lineal′ actuator acts in the direction to shorten itself, i.e., in the tension direction.
Further, in another conventional example proposed in Patent Document 3, in the same configuration as in Patent Documents 1 and 2, a drive shaft is installed between the other lateral side portions of the second links, and the moving members at the tips of boost arms installed on the drive shaft are engaged with the guide members installed on the other lateral side portions of the first links. A lineal′ actuator is provided to extend between the drive arms installed on the drive shaft and the one lateral side of the second links. Therefore, in this lift mechanism, the lift frame is raised when the lineal′ actuator acts in the direction to elongate itself.
In the conventional X-linked lift mechanisms as described above, the lineal′ actuator is provided to extend between the one lateral side and the other lateral side of the links, i.e., between both the lateral sides of the pivots at which the first links and the second links are connected with each other.    Patent Document 1: JP 8-217392 A Patent Document 2: JP 2002-320651 A Patent Document 3: JP 2005-348983 A